Heat conductivity apparatus



May z, 1944. R. A. BUTLAND 2,347,661

HEAT CONDUCTIVITY APPARATUS Filed Sept. 5, 1941 2 Sheets-Sheet 1 .,f I@zal WMM rMIM 2 1944-A R. A. BUTLAND 2,347,651

HEAT coNDuoTIVITY APPARATUS Filed Sept. 5, 1941 2 Sheets-Sheet 2 ture toproduce an Patented May 2, 1944 UNITED STATES PATENT OFFICE 2 claims.

(Granted underrthe act of March April 30, 1928; 370 0.

amended The invention described herein, if patented, may be manufacturedand used by or for the Government for governmental purposes without thepayment of any royalty thereon.

This invention relates to an apparatus which can be used to determinethe heat conductivity or relative insulation values of textiles or othermaterials under widely varying conditions simulating climatictemperature, humidity and wind velocity.

In the determination of how much warmer one fabric is than another, amatter of vital concern to the Army having troops in the field underextremely wide ranges of temperature, it is necessary, by suitablethermostatic controls, to maintain body temperature as far as possible,and in order to do this there is provided a cylinder in which agitatedwarm oil within the cylinder is maintained at a temperature ofapproximately 98.6 F., corresponding to internal body temperature.

It is, therefore, a fundamental object and purpose of this invention toprovide a practical apparatus whereby the diierence in warmth be- Ytween textiles and other materials can be accurately recorded and thevariations in the expenditure of electrical energy to maintain theinternal warmthv of the cylinder between diierent materials iscalculated to show the percentage that one material is warmer than theother.

' Therefore, this electrical control of the elements Within the testingroom permits varied types of tests to be made under wide ranges oftemperaand humidity for different periods of time and with changedconditions of wind velocity.

Another important object of the invention is apparatus wherein tests maybe conducted, both on uniform types of fabrics, which are subject tocold high winds where the factors of bre type, texture, textile densityand nish are of major importance and on fabric classes which areconstructed for use in still air, where the porosity of the textile isgreat and the insulation value depends in considerable degree upon thecapturing of warm air in the porous texture or in the protected positionof the materials employment.

Therefore, another important object of the invention is to produce anapparatus that can be operated under extremely adverse temperatureconditions, first with sub-Zero external temperatures with virtually nohumidity andsecond with tropical external temperatures with a very highrelative humidity, thereby simulating ytropical conditions. Theapparatusl itself could be 3, 1883, as G. 757) removed from theinsulated room and transported to positions in these diierent climatesto make tests, using the actual temperatures and wind conditions forcomparisons.

Still another object of the invention is to produce an apparatus wherebythe accurate determination of the heat transfer through textiles orother materials is determined through the use of a copper cylinder whichis lled with oil or other medium and internally controlled bythermostatic means, to maintain a temperature of approximately 98.6 F.,while at the same time the external temperatures in an insulated room inwhich the copper cylinder is located are accurately controlled fromtropical temperatures to sub-zero temperatures and the air surroundingthe cylinder on which the textile or other material is placed Variesfrom comparatively motionless to gale intensity.

It is known that there are now in use various apparatus and methodswhereby determinations of heat conductivity may be attempted. However,in several of the known apparatus the sample of textile or materialtested is of such minute dimensions that the normal variations intexture occurring in manufacturing cannot be compensated for. Therefore,the invention was developed to test large areas of fabric, preferably,but not limited, to rectangular pieces 36 by 40 inches, so that theuneven characteristics normal to weaving, knitting, braiding, spinning,finishing and other processing of textiles, or in the manufacturing ofother substances, may be equalized.

Several types of known apparatus are thermostatically controlled andhave depended upon the conduction of heat from the controlled heatsource, through the textile to cooler temperatures, thereby dependingupon the measurement of electrical expenditure and difference in wattageexpended to determine the difference in relative Warmth. l

This invention has been devised, therefore, to permit a new and usefulmethod of `determining the warmth of textiles by taking intoconsideration thatv clothing d oes not completely surround the trunk orlimbs of the body but drapes itself on the body, permitting air-spacesbetween the body andthe textile surrounding it. These air spacesjheldcaptured warmvair, which insulate the-body and are of major importancein the determination of relative Warmth in items of clothing.- y

In this invention these isolated air spaces are simultated by mechanicalmeans, the material having alternate contacts in certain types of testsbetween the circumference of the copper cylinder and metal ns, therebyestablishing air spaces that are similar to those prevalent when theclothing is Worn by an individual. This constancy in the size and extentof the air spaces, being the same size when different materials aretested, equalizes the insulation value of air spaces between fabrics andmakes for accuracy in the heat conductivity tests.

The apparatus can realistically` simulate a cold, Warm, dry or wet windblowing against the limbs or trunks of an individual. Therefore,there isprovided an apparatus which maybeused in the simplest routine testingaswell 'asina most complex series of tests, either in an insulated roomor at widely separated places, and introducing wide variables inairmotion, external temperature and humidity.

The accomplishment of the above and'other i related objects is embodiedin the forms illustra'tedin the accompanying drawings, wherein theinvention is shown consisting of features of construction, arrangementand application of parts, `which will appear in the specification and befinally pointed out in the claims, and While the preferred embodiment ofthe invention is shown it will be understood thatslight changes in formand minor details of construction may be resorted to without departingfrom thespirit of the invention.

"Referring now to; the 'drawings in which similar characters andreferences in the several figures indicate identical parts:

'Fig 1 is a front elevation of the preferred Aform of the inventiomwithan insulated room shown'in section.

Figg2 is an enlarged longitudinal section of the `Vpreferred form oftheinvention, taken on line A2--e2 *of* Fig. 1.

:'Fig. 3 is a'horizontal'sectionV taken on line '3.-3 `of* Fig. 1.

Figgi is an elevation of the frame Work used when' textiles orothermaterials are being subjected to certain types of tests requiringair spaces, Y Y`1ig.'5 is an Velevation of the frame work with 'thetextile or other -material in place. y A 'Fig. 6 is ahorizontalsectiontaken on line 6--8 of Fig." 5.

Referencenowbeing made to'the drawings by'numeral'and more particularlyto Figs. 1 to 3 inclusive, in which is shown, by yway of example Aandnot as a limitation, one vform ofthe invention, in which thefrapparatus-is shown asa single complete* system within an insulated room IU,

lmounted upon atable II, adapted -to support a backboard I2 throughwhich the air funnel I3 isplaced so that variable-air velocity can bein- 1 troduced 'against the surface-of the textile or other material I4which is adapted to-be mounted on a copper cylinder I5 which has itsexterior painted with black lacquer. The cylinder I5 is closed at-bothends by a copper top and bottom Litin such amanner that depressions I'Iare formed vat both ends, vinto which are inserted-at both top andbottom cork covers I8, upon which is placed reinforcing material gli).Extending down into the oil filled cylinderf'is a copper Well 29 whichis' formed as an integral part of thev top i6, within this wellv thereis suspended an electronic thermo regulator 2|, the bulbfoi which rissurrounded, inside the well, 'by anysuitable heatconducting medium'22.lThe stemV of vthe 'regulator' 2 I 'extends Iupward int'tran operi-ingV2 3" oil at a mean temperature of 98.6 F. The oil is adapted to. beagitated so that a uniform tem- -perature is maintained on all theexternal surfaces of the cylinder I5 by an agitating propeller AZI whichisadapted to be driven by a shaft 28 which is connected to a motor 29which is at 4ktached to the top reinforcing material i9, current beingSupplied to the motor 29 by electrical connections`30.

The entire unit as previously described i; adapted to be Yplacedv.within the air control jacket 3|, the air funnel I3' previouslydescribed is a part of and integral with thisjacket 3I The air velocity.against the textile or other material is controlled by a variableV airvelocity fan 32 ,and the air escaping from the Yair control jacket `3|isA emitted through the open top of the air controlled jacket l3| .andthrough vents 33at the bottom of the jacket,

Access is gained to the interior of the jacket 3| by means of a hingeddoor 34 in the f'front ofthe air jacket" SI. This. permits Aan Operatorto remove and replace the material to be tested. Conventional latchesl35nare used to vkeep the door in closed position.

It is t0 be-un'derstood that while the foregoing description covers afixed or stationaryapparatus it may Well be built of a mobile type or.other construction -inlany suitable manner, so longas it embodiestheiessential variable-airinduction air funnel, the jacket surrounding aheated cylinder and the introduction of variable `air currents againstthe surface of -a textile or other material underneath which areV either`alternate contacts with the -copper heat-radiating cylinder andcaptured `air spaces inone type -of test and completelywrapped aroundthe cylinder in the other. It is also to be -understood that vwhilethere -is disclosed a heat conductivity yapparatusemploying a cylinderpainted on its exterior surface with a'black lacquer, with ends-ofcopper insulated -with cork covers'to preventthe escape ofheat, at thetopand bottom,=an electicularftype of heating elementand propellingmeans,-they arel not to Abe considered as of a limitingnaturefas itisWithin the scope ofthe invention to provide-'various metals,materials, shapes,'constructions, heat controlling devices, lheatingelements, different AVmethods of agitating is yadapted to providethemost usefulI and` coni venient disposition thereof to suit theparticular installationr and` maintain- -controlled temperaturesjwithoutdeparting-'from the scope off-the invention.

The apparatus previouslyedescribed is -controlled by a panelboard36,-Which is placed out- `A`room- I 0 has acompressor control4 bulb' 40which controls the compressor 4I mounted outside of the testing roomII), alternately starting and stoppingthis compressoras the temperaturerises and falls within the testing room I by the ordinary method ofrefrigeration. In order to acjcomplish this purpose the compressor 4Icirculates the refrigerant through the diffuser' 42 withinv the `testingroom I0 by connections 43 and 44. diffuser the usual electric diffuserfan l5 which by its operation forces the air downward through thediffuser and out through hinged doors 45 on the bottom of the diffuser.'A specially calibrated watt hour meter 4l registers the expenditure ofcurrent required to maintain the temperature within the oil lledcylinder I5. A three heat switch 48 permits a variation in the heatexpenditure required inside of the cylinder to meet the dierentrequirements from tropical temperatures to sub-zero temperatures.Electrical switches 49 control the diffuser fan 45, the motor 25, lightmeans within the testing room I0, variable velocity fan 32 and any otherelectrically controlled means that may be required to maintain theoperation of the apparatus. A red pilot light i) is used as a warn-There is also shownas a part of the ing signal to indicate whether theapparatus f is in operation or not. A relay 5I cuts the current in andout of the heating element 26 as the mercury column rises and fallsbetween the contacts of the electronic thermoregulator 2l, resultingfrom the temperature rise and fall within the oil filled cylinder I5,preferably within a fraction of a degree. There is also placed on thecontrol panel board a fuse box 52 which controls the electricalequipment to prevent serious damage to the apparatus by a short circuitor other failures in the electrical equipment. A rheostat 53 is used asa resistance to increase and decrease the speed of the propeller motor29 to produce the most uniform distribution of heat over all externalsurfaces Y of the copper cylinder I5. As has already been stated, thepanel board 3S is placed on the outside of the testing room IE! topermit a control of the various elements of the apparatus within thetesting room and thereby enable the necessary readings and calculationsto be made without disturbing the atmospheric conditions within thetesting room.

The apparatus previously described discloses one type of test wherein apiece of material is being tested, by completely wrapping the cylinderl5 without the framework shown in Fig. 4. Figs. 4 to 6 inclusive showanother method whereby a piece of material can be tested with alternateair spaces underneath. In order to accomplish the purpose in the secondmethod there is provided an air spaced harness 54 having iins 55thereon, which produces air spaces 56 adapted to simulate the drape ofcloth on the body and as previously stated, assists in protecting thebody warmth of the individual. Any number of fins may be attached to theharness and arranged either vertically, horizontally, diagonally orotherwise, and the invention is not to be considered as limited to thisparticular construction, since a fluted cylinder holding the heatingmedium would provide the alternate contacts and captured air spaces andstill lie within the scope of the invention.

During this particular type of test the air space harness is placed overand surrounds the oil filled copper cylinder I5 and the textile or othermaterial I4 to be tested is wrapped around the air spaceharness 54 andoil lled cylinder I5 lunder suitable tension and the ends thereof areclipped to one of the ns 55 by suitable clips 5l. The textile is finallycompressed against the top and bottom covers I9 of the cylinder I5 withmetal bands 58, which are provided with suitable tightening device 59.As stated, this canI be accomplished by opening the air controlledjacket door 34 which can then be closed and retained in closedposition'bylatches 35.

In this manner the ns 55 of the air space harness 54 can be so arrangedthat air currents impinging upon the surface of the textile `or othermaterial, can simulate a freezing wind forcing the material against awarm skin surface, the material rapidly conducting away the bodilywarmth, and the difference in the thermal conductivity between fabricsdetermines the true insulation value of the material.

While there have been described two types of tests wherein a singlelayer of cloth is wrapped completely around the heated cylinder as shownin Fig. 3 and a single layer of cloth around the air space harness asshown in Figs. 4, 5 and 6, it is within the scope of the invention towrap two or more layers of cloth either around the cylinder or over theair space harness, or one layer around the cylinder, adjusting the airspace harness and adding one or more layers, over the air space harness,in order to simulate one or more external uniform fabrics and a lighterunderwear or undergarment fabric, so as to determine the relative warmthof a combination of two or more fabrics. It is likewise within the scopeof the invention to place a second harness over the cloth wrapped aroundthe rst harness, in order to have an additional set of air spaces whichwould furtherV simulate the normal drape of fabrics in externallgarments, underwear, shirts, etc.

The fins may also be attached to the surface of the heated cylinder inany suitable manner other,

" in the art, that the several embodiments of the invention hereindisclosed accomplish the principal object of the invention. It also hasuses and advantages other than those herein particularly referred to.Also, that various other changes and modifications than those alreadypointed out may be made Without departing from the spirit of theinvention and since the embodiments disclosed herein, being onlyillustrative of the device, the invention is not to be understood asrestricted thereto, since these may be modified within the scope of theappended claims without departing from the spirit and scope of theinvention.

Having thus described the invention, what is claimed as new and desiredto secure by Letters Patent is:

l. Apparatus for testing the heat conductivity of textiles comprising aninsulated chamber, a metal cylinder containing a fluid medium insidesaid chamber and spaced from the walls thereof, means for heating saidfiuid medium, means responsive to the temperature inside the cylinderfor controlling the energy supplied to the heating means to maintain thetemperature inside the cylinder at a constant temperature, means forcontrolling the temperature inside of the insu..

lated chamber, a fan for cireulating yair vWithin the'fch'amber at aselected MelOcity, said cylinder being adapted to have a textile v tohe" tested Wrapped about the same, and means to measure the 'energysupplied to the lmeans -for heating the uid `medium to maintain theinside of the cylinder at a Yconstant, tempertaure las an index of theheat lconductivity of the textile under test. 2. Apparatus for testingthe heat conductivity of textiles comprising an insulated chamber, acontainerA of 4heat conducting material containing a fluid medium insidesaid Chamber and spaced vfrom the walls thereof, means for heating saidfluid medium, means responsive to the temper.-

ature inside the ccontainer for controlling the energy supplied .to .theheating means temainf tain ,the "temperature inside ,the container at aconstant temperature, means lfor controlling the temperature inside ofthe insulated Chamber, a fan for circulating air within the chamber at aselected veloctiy, said container being vadapted to have a textile to betested Wrapped about the same, and means tomeasure the venergy suppliedto the means vfor heating the fluid medium t9 maintain the .inside of,the Qontainer at a 90.11: stant temperature as an index vof the heatconductivity of the .textile under test.

,RALPH ,Af BUTLAND

